U.S. patent number 5,268,394 [Application Number 08/015,329] was granted by the patent office on 1993-12-07 for stabilization of polyoxyalkylene polyether polyols.
This patent grant is currently assigned to Uniroyal Chemical Company, Inc.. Invention is credited to Lawrence B. Barry, Mark C. Richardson, Edward L. Wheeler.
United States Patent |
5,268,394 |
Wheeler , et al. |
December 7, 1993 |
Stabilization of polyoxyalkylene polyether polyols
Abstract
The invention relates to the use of an acridans of Structure (I)
as a stabilizer, preferably combined with hindered amine, phenolic,
and phosphite stabilizers for stabilizing polyether polyols for
polyurethane flexible foams and as stabilizers for the polyglycols,
heat transfer fluids, lubricating additives. ##STR1##
Inventors: |
Wheeler; Edward L. (Watertown,
CT), Barry; Lawrence B. (Newington, CT), Richardson; Mark
C. (Cheshire, CT) |
Assignee: |
Uniroyal Chemical Company, Inc.
(Middlebury, CT)
|
Family
ID: |
26687246 |
Appl.
No.: |
08/015,329 |
Filed: |
February 9, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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756745 |
Sep 9, 1991 |
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Current U.S.
Class: |
521/108; 521/117;
521/121; 521/128; 524/120; 524/128; 524/153; 524/258; 524/291;
524/349; 524/89 |
Current CPC
Class: |
C08K
5/3437 (20130101); C10M 133/02 (20130101); C10M
133/40 (20130101); C10M 141/06 (20130101); C10M
141/10 (20130101); C09K 15/30 (20130101); C10M
2223/10 (20130101); C10M 2205/00 (20130101); C10M
2207/023 (20130101); C10M 2207/024 (20130101); C10M
2207/026 (20130101); C10M 2207/027 (20130101); C10M
2209/104 (20130101); C10M 2215/00 (20130101); C10M
2215/06 (20130101); C10M 2215/064 (20130101); C10M
2215/065 (20130101); C10M 2215/066 (20130101); C10M
2215/067 (20130101); C10M 2215/068 (20130101); C10M
2215/22 (20130101); C10M 2215/221 (20130101); C10M
2215/225 (20130101); C10M 2215/226 (20130101); C10M
2215/30 (20130101); C10M 2219/108 (20130101); C10M
2223/02 (20130101); C10M 2223/04 (20130101); C10M
2223/041 (20130101); C10M 2223/042 (20130101); C10M
2223/049 (20130101) |
Current International
Class: |
C08K
5/00 (20060101); C09K 15/00 (20060101); C08K
5/3437 (20060101); C09K 15/30 (20060101); C10M
133/02 (20060101); C10M 141/00 (20060101); C10M
141/10 (20060101); C10M 133/40 (20060101); C10M
133/00 (20060101); C10M 141/06 (20060101); C08K
005/18 (); C08K 005/34 (); C08K 005/46 (); C08K
005/49 () |
Field of
Search: |
;524/89,120,153,128,258,291,349 ;521/108,117,121,128 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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EP502520 |
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Sep 1992 |
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IT |
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1085082 |
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Sep 1967 |
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GB |
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Primary Examiner: Michl; Paul R.
Assistant Examiner: Yoon; Tae H.
Attorney, Agent or Firm: Thompson; Raymond D.
Parent Case Text
This is a continuation of application Ser. No. 07/756,745 filed
Sep. 9, 1991 now abandoned.
Claims
What is claimed is:
1. A sulfur-free oxidizable polyoxyalkylene polyether polyol
composition stabilized against thermal and oxidative degradation by
the incorporation therein of a minority amount of a stabilizer
system consisting essentially of:
(a) at least one acridan compound provided that the acridan
compound(s) is(are) represented by the structure: ##STR7## wherein
R.sub.1, R.sub.2 can be H, C.sub.1 -C.sub.18 alkyl or C.sub.7
-C.sub.18 aralkyl and R.sub.3 and R.sub.4 may be aryl or C.sub.1
-C.sub.18 alkyl or C.sub.7 -C.sub.18 aralkyl,
(b) a amine stabilizer of the structure ##STR8## wherein R.sub.5
and R.sub.6 are individually selected from H, C.sub.1 -C.sub.18
alkyl, and C.sub.7 -C.sub.18 aralkyl, and
(c) a phenolic stabilizer of the structure ##STR9## wherein R.sub.9
can be C.sub.1 -C.sub.18 alkyl or C.sub.7 -C.sub.18 aralkyl and
R.sub.7 and R.sub.8 are C.sub.4 -C.sub.12 alkyl or C.sub.7
-C.sub.12 aralkyl.
2. The oxidizable composition of claim 1 consisting essentially
of:
a phosphite stabilizer of the formula: ##STR10## wherein R.sub.10
and R.sub.11 are independently selected from C.sub.6 -C.sub.18
alkyl, aryl, C.sub.7 -C.sub.18 aralkyl, or C.sub.7 -C.sub.18
alkaryl.
3. The oxidizable composition of claim 1 wherein R.sub.1 and
R.sub.2 are hydrogen and R.sub.3 and R.sub.4 are alkyl.
4. The oxidizable composition of claim 1 wherein R.sub.1 and
R.sub.2 as hydrogen and R.sub.3 and R.sub.4 as methyl.
5. The oxidizable composition of claim 1 wherein R.sub.5 and
R.sub.6 are alpha,alpha-dimethylbenzyl.
6. The oxidizable composition of claim 1 wherein R.sub.9 is
sec-butyl or methyl and R.sub.7 and R.sub.8 are t-butyl.
7. The oxidizable composition according to claim 1 wherein the
acridan is present in the amount ranging from about 1 to about 10%
by weight.
8. The oxidizable composition of claim 1 wherein said acridan is
present in from about 0.1 to about 2.0 weight percent with the
remainder of said oxidizable composition being polyglycols, heat
transfer fluids, and hydrocarbon oils, greases or lubricants.
9. The manufacture of flexible polyurethane slabstock manufactured
from an isocyanate and polyether polyols stabilized by the
stabilizer system of claim 1.
10. A polyether polyol composition stabilized against degradation
comprising:
(a) a polyether polyol and;
(b) a stabilizer system consisting essentially of:
1) at least one acridan compound provided that the acridan
compound(s) is(are) represented by the structure: ##STR11## wherein
R.sub.1, R.sub.2, can be H, C.sub.1 -C.sub.18 alkyl or C.sub.7
-C.sub.18 aralkyl and R.sub.3 and R.sub.4 may be aryl or C.sub.1
-C.sub.18 alkyl or C.sub.7 -C.sub.18 aralkyl; and
2) additionally a highly hindered amine compound and a phenolic
compound, both compounds being known to exhibit stabilizing
properties.
11. The oxidizable composition of claim 10 wherein said additional
amine compound consists essentially of:
an amine stabilizer of the structure ##STR12## wherein R.sub.5 and
R.sub.6 are individually selected from H, C.sub.1 -C.sub.18 alkyl,
C.sub.7 -C.sub.18 aralkyl, or C.sub.7 -C.sub.18 alkaryl.
12. The composition of claim 10 wherein said additional phenolic
compound consists essentially of:
a phenolic stabilizer of the formula ##STR13## wherein R.sub.9 can
be C.sub.1 -C.sub.18 alkyl, C.sub.7 -C.sub.18 aralkyl, or and
R.sub.7 and R.sub.8 are C.sub.4 -C.sub.18 alkyl, C.sub.7 -C.sub.12
alkyl.
13. The polyether polyol composition of claim 10 further consisting
essentially of:
a phosphite stabilizer of the formula IV
14. A composition according to claim 1 further consisting
essentially of comprising a phenothiazine.
Description
FIELD OF THE INVENTION
The present invention relates to the stabilization of
polyoxyalkylene polyether polyols and the use of the stabilized
polyols in the preparation of polyurethane foam. In particular the
invention relates to stabilization of polyols with certain
stabilizer compositions and the color stability or scorch
inhibition of flexible and semiflexible polyurethane foams made
from the stabilized polyols.
BACKGROUND AND RELATED ART
Prior art methods for the stabilization of polyalkylene polyether
polyols with antioxidants or stabilizers and the use of stabilized
polyols in the preparation of polyurethane foams to inhibit scorch
are well known. Polyether polyols, used in the manufacture of
slabstock flexible urethane foam, are typically stabilized with
antioxidant packages consisting of phenolic and amine antioxidants,
and may also contain the synergist phenothiazine.
U.S. Pat. Nos. 3,567,664 and 3,637,865 disclose polyurethane foams
stabilized with a mixture of 2,6-di-tert-butyl-4-methyl phenol
[butylated hydroxy toluene (BHT)] and p,p'-dialkyldiphenylamines.
U.S. Pat. No. 4,010,211 teaches the addition of phenothiazine to a
BHT/p,p'-dialkyldiphenylamine mixture. U.S. Pat. No. 4,794,126
discloses flame-retardant polyurethane foams stabilized with a
combination of a diarylarylenediamine, a reaction product of
diarylamine and alkyl ketone and a hindered phenol, specifically
3,6'-di-tert-butyl-4-sec-butyl phenol.
U.S. Pat. No. 4,933,374 discloses polyoxyalkylene polyether polyol
compositions protected against oxidative degradation with a
stabilizing amount of a synergistic mixture of
2,6-di-tert-butyl-4-sec-butyl phenol and a reaction product of
diisobutylene, styrene, and diphenylamine wherein the weight ratio
of the diisobutylene to the styrene is from about 2:1 to 5:1.
U.S. Pat. No. 4,551,493 is concerned with transparent
flame-retardant poly(arylether-arylsulfone) molding materials. An
example of a heat stabilizer given is a hindered phenol and a
diphenylamine/acetone condensate. In this patent, the final product
is used as a flameproofing agent for plastic molding materials.
Certain simple acridan compounds of the instant invention are
disclosed but not exemplified as useful in stabilization of the
sulfur bearing poly (aryletherarylsulfone) polymers. Furthermore,
the cyclic or linear diphenylamine/acetone condensate of U.S. Pat.
No. 4,551,493 are used in combination with a
poly(2,6-dibromophenylene 1,4-oxide). The compositions of the
instant invention are not halogenated in any manner nor do the
stabilized polymer chains contain a sulfur linkage.
Antioxidants are used in polyether polyols to protect the polyol
from oxidation during the final stages of manufacture; to reduce
peroxide formation during storage; and to reduce the possibility of
scorching the flexible polyurethane slabstock foam due to thermal
oxidative degradation.
The compounds of this invention are particularly important to the
polyol/flexible urethane industry due to the increased concern over
chlorofluorocarbons (CFCs) and their deleterious effect on the
earth's ozone layer. CFCs are incorporated in flexible slabstock
foam to serve as an auxiliary blowing agent and for the removal of
heat during slabstock production. The absence of CFCs places a
higher performance requirement on the stabilization system, since
the CFCs prevent discoloration, physical scorch and self-ignition
of the foam.
The presence of scorch is of major concern to the foam
manufacturers since it negatively affects the appearance of the
product, causes physical damage and may result in fire. Recent
regulations eliminating the use of CFCs in polyurethane foam
manufacture require enhanced scorch protection during flexible
slabstock foam production.
It would therefore be advantageous to have a antioxidant system for
polyether polyol stabilization that provide increased scorch
protection, allow foams to be produced at higher internal
temperatures, and eliminate the use of CFCs without adverse effects
to the foam.
Accordingly, it is an object of this invention to provide a
stabilizer system for polyether polyols which provides valuable
protection for oxidation, scorching, and discoloration of resultant
foam produced, including those foams produced containing flame
retardants.
It is a further object of this invention to provide an
environmentally friendly stabilization package for polyether
polyols. More specifically, a stabilization package which holds the
possibility of eliminating the need for chlorofluorocarbons,
heretofore used in flexible polyurethane foam production.
It is a still further object of this invention to provide a
flexible polyurethane foam product made from the stabilized polyol
together with an isocyanate with improved scorch performance,
appearance, and color.
The foregoing and additional objects will become more evident from
the following description and Examples.
SUMMARY OF THE INVENTION
The stabilizers of the instant invention is comprised of a class of
amine stabilizers, known as acridans, which shows efficacy as well
as unexpected synergy when combined with traditional amine,
phenolic, phenothiazine and phosphite stabilizers in stabilizing
polyether polyols for polyurethane flexible foams which may contain
flame retardants as well as other non-sulfur contained polymers
subject to heat and oxidane degradation.
Another aspect of this invention concerns a method for the
stabilization of polyalkylene polyether polyols against oxidative
degradation and the use of such a stabilized polyol together with
polyisocyanates to prepare scorch stabilized polyurethane
foams.
Yet another aspect of this invention concerns a method of
stabilizing polyglycols, heat transfer fluids, lubricating
additives, and the like using the synergist of this invention with
traditional stabilizers to increase the efficacy of the stabilizer
system and enhance the properties of the respective products.
DETAILED DESCRIPTION OF THE INVENTION
In one aspect, the instant invention is directed to the use of:
##STR2## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 can be H,
C.sub.1 -C.sub.18 alkyl, or C.sub.7 -C.sub.18 aralkyl. R.sub.3 and
R.sub.4 can also be aryl, preferably phenyl.
The term, "acridan", as depicted in structure I above will be used
hereinafter to refer to the group of compounds structurally
represented by (I). The acridan may be optionally combined with an
amine stabilizer of the structure II ##STR3## wherein R.sub.5 and
R.sub.6 can be H, C.sub.1 -C.sub.18 alkyl, C.sub.7 -C.sub.18
aralkyl, a phenolic stabilizer of structure III ##STR4## wherein
R.sub.9 can be C.sub.1 -C.sub.18 alkyl or C.sub.7 -C.sub.18 aralkyl
and R.sub.7 and R.sub.8 are C.sub.4 -C.sub.12 alkyl, C.sub.7
-C.sub.12 aralkyl, preferably t-butyl; or optionally combined with
a phosphite stabilizer of the formulas IV or V. ##STR5## wherein
R.sub.10 and R.sub.11 are independently selected from C.sub.6
-C.sub.18 alkyl, aryl, C.sub.7 -C.sub.18 aralkyl, or C.sub.7
-C.sub.18 alkaryl.
Examples of such known stabilizing amines, phenols, and phosphites
include dioctyl diphenylamine, butylated hydroxytoluene,
(2,6-di-t-butyl-4-methylphenol), phenothiazine,
4,4'-bis(alpha,alpha-dimethylbenzyl) diphenylamine, styrenated
diphenylamines, diisobutylated diphenylamines, mixtures of
styrenated and diisobutylated diphenylamines, mixtures of
styrenated and .alpha.,.alpha.,dimethylbenzyl diphenylamines,
mixtures of butyl, dibutyl, and octyl diphenylamines, dimerized
2,2'-methylene bis-6-t-butyl-p-cresol, 2,6-di-t-butyl
4-sec-butylphenol, tris(nonylphenyl) phosphite,
tris(2,4-di-t-butylphenyl) phosphite and the like.
Preferred substituents of Structure I include those when R.sub.1
and R.sub.2 are hydrogen and R.sub.3 and R.sub.4 are alkyl. A more
preferred substitution would include R.sub.1 and R.sub.2 as
hydrogen and R.sub.3 and R.sub.4 as methyl.
A preferred amine compound for the stabilizer package of this
invention includes structure II above wherein R.sub.5 and R.sub.6
are .alpha.,.alpha.,dimethylbenzyl.
A preferred phenolic stabilizer of this invention includes
structure III above wherein R.sub.9 =sec-butyl or methyl and
R.sub.7 and R.sub.8 are t-butyl.
The stabilizer system containing an acridan along with currently
used commercially available stabilizers will contain from 1 to 50%
by weight of the acridan component in the polyether polyol
stabilizer system. A preferred range is from 2 to 20% by weight of
the acridan component in the polyether polyol stabilizer system. A
most preferred range is from 2 to 10% by weight of the acridan
component in the polyether polyol stabilizer system.
In another aspect, this invention relates to the manufacture of
flexible polyurethane slabstock manufactured from polyether polyols
stabilized by the compositions described herein.
The commercially available amine and phenolic antioxidants utilized
in the compositions of this invention are known by several
trademarks including NAUGALUBE.TM. 680, 635, or 640 brand amine
antioxidants, NAUGARD.TM. 445 brand
4,4'-bis-(alpha,alpha-dimethylbenzyl)diphenylamine antioxidant;
NAUGARD.TM. BHT brand 2,6-di-t-butyl-4-methylphenol antioxidant,
NAUGARD.TM. PS-20 brand styrenated diphenylamine antioxidant,
NAUGARD.TM. PS-30 brand butylated octylated diphenylamine
antioxidant (trademarks of the Uniroyal Chemical Company);
ISONOX.TM. 132 brand 2,6-di-t-butyl-4-sec-butylphenol antioxidant
(trademark of Schenectady Chemical Company) and others. Other
commercially available antioxidants considered to be within the
scope of this invention include phenothiazine, phosphites,
bisphenols, and the like. These type products are well-known and
familiar to those skilled in the art. Acridans provide increased
performance in systems where simply increasing antioxidant levels
shows little or no increase in performance.
SYNTHESIS OF THE ACRIDANS
The acridan component of this invention was synthesized by the
following procedure: The low temperature reaction product of
diphenylamine and acetone is synthesized according to U.S. Pat. No.
2,202,934 (available as AMINOX.TM. from Uniroyal Chemical Company)
and 3% by weight iodine were heated to 240.degree. C. for four
hours. The crude reaction mixture, which contained diphenylamine,
dimethylacridan, isopropyl diphenylamine, and dimers and trimers of
various alkylated diphenylamines, was carefully fractionally vacuum
distilled. The portion boiling at 130.degree.-140.degree. C. at 0.3
mm Hg was collected. The desired product,
9,10-dihydro-9,9-dimethylacridan (abbreviated a AC1 in Table 1),
was recrystallized from hexanes. The product yield was <30%.
Other acridans of Structure (I) are made by an analogous reaction
of a p-di-alkylated diphenylamine with a ketone where the alkyl
substituents of the DPA are R.sub.3 and R.sub.4 and the ketone is
of the form ##STR6## where R is C.sub.1 -C.sub.18 alkyl, or aryl,
alkaryl (C.sub.7 -C.sub.18) or C.sub.1 -C.sub.18 aralkyl of
Structure I and other synthesis techniques and routes can be
contemplated to produce improved selectivity and yield.
Synthesis of AC2 and AC3 referring to Structure I, the compound
referred to hereinafter as AC2 has the following representative
structure: R.sub.1, R.sub.2 are t-octyl, R.sub.3 is phenyl and
R.sub.4 is methyl. AC3 compound has R.sub.1 and R.sub.2 =t-butyl,
R.sub.3 is phenyl and R.sub.4 is methyl.
A di-p-t-octyl-diphenylamine was reacted with acetophenone to form
the acridan AC2; in the case of AC3 di-p-t-butyl diphenylamine was
reacted with acetophenone. This AC2 and AC3 compounds demonstrated
excellent utility although AC1 is slightly superior; therefore, AC1
is highlighted in the subsequent comparisons with commercial
control stabilization systems.
STABILIZER PACKAGE PREPARATION
The acridan component of the stabilizer package was combined with
commercially available amine and phenolic stabilizers including
dioctyl diphenylamine (abbreviated as dioctyl DPA),
2,6-di-t-butyl-4-methylphenol (butylated hydroxytoluene or BHT),
phenothiazine (PTZ), 4,4'-bis
(alpha,alpha-dimethylbenzyl)-diphenylamine (also known as
NAUGARD.TM. 445 and abbreviated in Table 1 as 445),
2,6-di-t-butyl-4-sec-butylphenol (also known as ISONOX.TM. 132 and
abbreviated as 132), a mixture of styrenated/diisobutylated
diphenylamine.(also known as NAUGALUBE.TM. 680) according to the
amounts listed in Table 1. Each combination was tested for
polyether polyol stabilizer performance.
EXAMPLES
TABLE 1 ______________________________________ Example Component A
B C D 1 2 ______________________________________ Dioctyl.DPA 2200
1950 -- -- -- -- BHT 2200 2150 2200 2150 -- 2150 PTZ -- 100 -- 100
-- -- 445 -- -- 2000 1950 -- 1950 680 -- -- -- -- 1950 -- 132 -- --
-- -- 2150 -- ACl -- -- -- -- 100 100
______________________________________
In order to demonstrate the effectiveness of the stabilizer systems
of this invention, they were evaluated against commercial
antioxidant stabilizer packages. Both the commercial and
experimental types of stabilizer systems are listed in Table 1. All
of the antioxidant packages were loaded into 3,000 average
molecular weight polyol at levels typically used by the major
polyol producers, ranging from 0.2 to 0.7 weight percent.
The polyols used in these tests were selected from the commercially
available polyols VORANOL.TM. 3137 brand polyether polyol
(trademark of the Dow Corporation) or NIAX.TM. 16-52 brand
polyether polyol (trademark of the Union Carbide Corporation). The
average molecular weight of these materials is approximately
3000.
The polyether polyols that were stabilized by these stabilizer
systems indicated in Table 1, were tested by differential scanning
calorimetry (DSC), thermogravimetrically analyzed (TGA) and APHA
color tested. The procedures and results of these tests are given
below.
TGA METHOD/ANALYSIS
Thermogravimetric analysis measures the dynamic relationship
between the temperature and the mass of a system. By comparing the
mass of a sample to that of a controlled system, the temperature at
which weight loss is experienced due to evaporation, decomposition,
or combustion may be determined.
In this evaluation, a sample weighing approximately 30 mg was
placed in the sample chamber of a Perkin-Elmer TGS-2 Thermo
Gravimetric Analyzer. The chamber was then equilibrated, under
nitrogen, to 130.degree. C. Once equilibrated, the gas in the
sample chamber was switched from nitrogen to air at a flow rate of
100 cc/min and the temperature ramped at 5.degree. C./min until
100% weight loss of the sample had occurred. Although actual foam
formulations contain many components which are not present in the
TGA test, it is considered an excellent means for initial screening
of antioxidant candidates. The data in Table 2 indicates that of
the various antioxidant packages, Samples 5 and 6, containing the
synergistic acridan compound of this invention, provide equivalent
or better performance than the commercial packages evaluated.
DSC ANALYSIS OF POLYOL
Differential scanning calorimetry (DSC) measures the endothermic or
exothermic heat of reaction and can give the precise temperature of
this initial reaction. A sample weight of approximately 30 mg was
placed in the sample chamber of a Perkin-Elmer DSC-2C. The
instrument was equlibrated, under nitrogen flow, to 130.degree. C.
Once equilibrated, the gas in the sample chamber was switched from
nitrogen to air at a flow rate of 100 cc/min and the temperature
ramped at 10.degree. C./min with the temperature in K recorded at
the time of the exotherm. The DSC results shown in Table 2 shows
samples 5 and 6, containing the synergist of this invention, to be
superior to all other packages evaluated.
Additionally, APHA color testing of the polyols stabilized with
samples 1-6, as well as an unstabilized polyol sample, are
presented in Table 2. The APHA Platinum-Cobalt system used follows
ASTM D1209. The values on this scale range from 0 (water white) to
300 (cream white). This data is presented because of the importance
of color to the polyol manufacturers. The lower values, indicating
lightest color, are those most desirable.
It can be seen from the data that the addition of any stabilizer
package adds to the APHA, but the value of sample 2, with
stabilizer package containing the synergistic compound of this
invention, is equal to the lowest value for a commercially
available stabilizer package.
TABLE 2 ______________________________________ APHA TGA
analysis:weight DSC loss (.degree.C.) Example # (K) color initial
10% 20% ______________________________________ A 496.1 30 202 230
230 B 503.0 35 215 236 242 C 492.9 25 203 224 233 D 503.3 30 211
227 236 1 505.4 30 212 238 244 2 504.2 25 212 236 243
______________________________________
The aforementioned polyether polyols are used in the production of
slabstock flexible polyurethane foam. Samples of polyurethane foam
were made and tested by thermogravimetric analysis and microwave
scorch as well.
Testing conditions used to evaluate polyurethane foam samples were
the same as conditions used in the evaluation of polyol by TGA
(described above) except that the sample weight was approximately 8
mg because of the increased density of the foam. Platinum wires
were used to compress the foam samples onto the aluminum sample pan
in order to obtain a reasonable sample weight.
The small hand-mixed foam samples were made by the procedure below,
and is typical of formulations used by the polyol manufacturers. A
premix of 10.0 grams of water, 0.30 grams of an amine catalyst
DABCO.TM. 33-LV brand triethylene-diamine sold and trademarked by
Air Products & Chemicals) and 2.0 grams of a surfactant
(L-5810, a tin catalyst sold by Union Carbide) was added to 200
grams of a 3000 average molecular weight polyether polyol which had
minimal initial stabilization (100 ppm BHT) but also containing the
stabilizer package indicated in Table 1. The formulation may also
contain a flame retardant as used by foam manufacturers. These
flame retardants are typically chlorinated, chlorinated and
brominated or brominated phosphates. The mixture was stirred for
five seconds in a high speed Lightning Mixer. Then 0.40 grams of
tin catalyst (stannous octoate in dioctylphthalate) was added and
the resulting mixture stirred for five seconds in the Lightning
Mixer. Finally, 126.0 grams of toluene diisocyante (TDI-80, 80%
2,6-/20% 2,4-toluene diisocyante sold by Mobay) was added and the
mixture stirred in the Lightning Mixer for 7 seconds and
subsequently poured into a 10".times.10".times.5" cardboard box.
The foam was allowed to rise completely at room temperature.
These foams were not subjected to any additional heating either by
microwave or air circulating oven. The foam buns were allowed to
stand for a day, with samples taken midway between the center and
the outer surface of the foam bun. Table 3 shows the performance of
the commercially available as well as the experimental stabilizer
packages that are the subject of this invention. Examples 1 and 2
demonstrate superior performance as compared to comparative
Examples A-D.
The microwave scorch test is a rapid and reproducible small scale
test which correlates well with observed results from large machine
prepared foams. This procedure utilizes small hand mixed foam
samples in order to evaluate the effectiveness of antioxidant
packages. Because foam buns will dissipate the internal heat more
rapidly than foam buns produced on an industrial scale, a microwave
oven is used to uniformly heat the foam bun by radiant energy
rather than by conduction of heat. This promotes uniform heating of
the small foam bun resulting in reproducible scorch values. The
formulation used to prepare the foam buns is given above, and is
typical of the formulations used in the industry.
After the formulation was prepared, it was poured into a
10".times.10".times.5" cardboard box and allowed to rise. Five
minutes after the appearance of bubbles on the surface of the foam,
the sides of the box are pulled away from the foam bun and
immediately placed into a preconditioned microwave oven for 5
minutes and 30 seconds at 60% power. The microwave oven is
preconditioned by heating a 1000 ml beaker containing 600 ml of
water for 30 minutes prior to the first foam bun tested, with a
fresh beaker returned to the microwave for each bun tested, to
maintain a constant temperature and humidity within the microwave
during testing.
Upon removal of the foam bun from the microwave oven, it is placed
into an air circulating oven for 3 minutes at 125.degree. C. to
cure the skin of the bun. Upon removal from the air circulating
oven, the foam sample was cut in half, perpendicular to the rise of
the foam and inspected for degree of scorch. A one-inch thick slice
is cut from the center of each bun and analyzed via a Hunter Lab
Colorimeter, Model D25M/L.
The Hunter Color values on both the B scale (measuring yellowness
or blueness) and the E scale (total color difference compared to
white) were compiled for all six samples and may be found in Table
3. These data demonstrate that comparative Example D provides the
highest scorch protection of the commercial systems evaluated,
while Example 1 provides a slight increase in scorch protection
over the Example C, while Example 2 provides a sizeable increase in
scorch protection over comparative Example D.
TABLE 3 ______________________________________ TGA:% WT Loss
Microwave Scorch Example # 190.degree. C. 250.degree. C. Hunter B
Hunter E ______________________________________ A 99.3 88.3 21 38 B
99.3 89.0 22 37 C 99.3 88.0 19 32 D 99.3 88.5 11 15 1 99.4 89.3 18
25 2 99.4 89.5 6 10 ______________________________________
STABILIZATION OF OTHER POLYMERIC SYSTEMS
The acridans of the invention may be used in a wide variety of
polymers and long chain hydrocarbons which do not contain sulfur
linkages in the chains. These may include polyolefins, petroleum
based oils, lubes and greases as well as polyalkylene glycols,
preferably polyethylene glycols and methoxy polyethylene glycols
such as the CARBOWAX.TM. brand polyethylene glycols family of
products (trademarked and marketed by Union Carbide Chemical and
Plastics Company). These oxidizable compositions benefit greatly
from use of the stabilizer systems described herein.
Various stabilization systems, including several containing the
acridan synergists of this invention, were evaluated in polyglycol.
The polyglycol used was P-2000 (a product of Dow Chemical) and the
stabilizers employed included the comparative control, BHT,
described above.
COMPARATIVE EXAMPLE E AND EXAMPLES 3-5
To a 10 gram commercial sample of P-2000 polyglycol, 1.0% of each
stabilizer package was added. The samples were evaluated via
differential scanning calorimetry as described above using a
Perkin-Elmer DSC Model 2C which was calibrated using an indium
standard. Approximately 7 mg of samples were weighed into an
aluminum pan and were equilibrated at 373K with nitrogen flow, and
then ramped at 10.degree. K./min with air flow of 50 cc/min until
exotherm. The content of each stabilizer package along with the
temperature to exotherm, is presented in Table 4 below.
TABLE 4 ______________________________________ Example # Component
E 3 4 5 6 ______________________________________ Naugard 445 -- 0.5
0.5 0.5 1.0 BHT 1.0 -- -- -- AC1 -- 0.5 -- -- AC2 -- -- 0.5 AC3 --
-- -- 0.5 Temp to 198 256 253 247 215 Exotherm (C.)
______________________________________
The above DSC results show a consistently higher temperature to
exotherm. The Acridans of the invention, AC1, AC2, AND AC3 show
markedly higher temperatures to exotherm than the recognized
control BHT, or when Naugard 445 is run by itself.
The data presented herein are intended to illustrate, but in no way
to limit the scope of the invention. Other variations will be
evident to those skilled in the art and such modifications are
intended to be within the scope of this invention as defined by the
following claims.
* * * * *